The present invention relates to a power supply control circuit and, more particularly, to a power supply control circuit for use in vehicle equipment, such as an automobile radio telephone.
A conventional power supply control circuit for use in an automobile radio telephone includes a power switch circuit which controls power supply to the telephone. To prevent an automobile battery from running out, the power switch circuit supplies power to the telephone in response not only to the depression of a power switch in the telephone but also to the turning-on of an ignition key, or switch. If the power supply is done in response only to the depression of the power switch, the automobile battery may run out.
In an emergency situation, however, the prior art power supply control circuit is not satisfactory. The user must operate at least two switches, i.e., the ignition switch and the power switch before dialing. Thus, he cannot quickly place a call in an emergency situation.